The present disclosure relates to a method of forming a semiconductor structure, and particularly to a method of surface treatment of a semiconductor-containing dielectric material for subsequent deposition of a dielectric metal oxide.
Nucleation of dielectric metal oxides, such as hafnium oxide, deposited by atomic layer deposition (ALD) is known to be affected by the surface conditions. The thickness and quality of dielectric metal oxides formed by ALD varies according to the surface conditions of an interfacial dielectric material, which is a semiconductor-containing dielectric material such as silicon oxide/oxynitride/nitride or a silicon-germanium oxide/oxynitride/nitride. Poor nucleation results in poor quality of dielectric metal oxides.
In addition, the thickness of an interfacial dielectric material increases with the atomic concentration of germanium in a silicon-germanium alloy material on which the interfacial dielectric material is formed by chemical or dielectric conversion. Thus, an interfacial dielectric material formed on a surface of a silicon germanium alloy is thicker than an interfacial dielectric material formed on a silicon surface employing the same processing conditions. When different semiconductor materials are used across different semiconductor device regions, e.g., across p-type field effect transistors and n-type field effect transistors, the total thickness of dielectric material layers including a dielectric metal oxide formed by ALD can be different due to the differences in thickness of the interfacial dielectric material. Such differences are not desirable because some type of devices incorporate an unnecessarily thick dielectric material layer.